Thermostatic control for pot-type burners



Oet. 5, 1943. M. 1 MUELLERETAL 2,331,29 THERMOSTATIC CONTROL FOR POT TYPE BURNERS Filed July 14( 1941 2 sheets-sheet l NWS V /Iwhwlh l, y fvm Jl NN d., 5, 1943. M. L. MUELLER ET AL 2,331,219 O THERMOSE'ATIC CONTROL FOR POT TYPE BURNERS Filed July 14, 1941 2 Sheets-Sheet 2 i jffr/j l. Nuelez and' Geoge /Yncnzcwzl Patented Oct. 5, 1943 THERMos'rA'rIc coNTRon' ron Por-'ritira` BURNERS Moritz L. Mueller, Grosse Pointe, andGeorge R Neumann,` St. Clair Shores, Mich., assignors to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois 'Application July 14, 1941, serial No. 402,348

'-4 claims. `(ci. 236-9) This inventionL relates to hot air heater systems and particularly to an arrangement for effecting the transition from low fire to high fire and viceversa, having special application to oil pot burner heaters.

The ultimate to be achieved in the operation of oil pot burners is complete combustion for all values of heat output varying from that at low fire to that at high fire. The diiiiculty in accomplishing this result is of course due to the several variables present in the operation of this type of system, these including the control of the variable rate of oil feed to the burner; and the degree of heat present in the space to be supplied with warm air circulated from the heater. Any over! feeding of the fuel oil in effecting a transition eluded thermostatic means located in the space to be supplied with warm air and operable to control the oil feed to the burner, such means even including certain forms of limited delayed action means such as dash pots, and electrically heated warp elements.

It is an object of the present invention to pro'- vide an improved arrangement of control devices for correlating'the supply of fuel oil to the burner pot and the circulation of heated air through the heater whereby the required relatively long delayed action of the fuel oil feed valve is accomplishedlduring the transition from low fire to high fire and vice-versa to thus obtain complete combustion under all conditions of operation.

It is a more particular objectto provide in a combination of the above type a definite corre-,- lation between the means for creating a forced draft and the means for regulating the flow of fuel oil t'o the burner pot this correlation including a relatively long delayed action between the operation of these two instrumentalities.

It is a still further detailed object to provide an air heater of the present type wherein the air is brought into contact with the exterior heating surface of the stove at least twice before acting on the heat sensitive fuel control device and wherein a forced draft producing means is incorporated in lseries with the means for effecting feed regulating valve assembly; and

Figure 4 is aschematic' layout of a modified form of the present invention.

Referring in greater detail to the figures of the drawings and particularly to Figure 1, numeral I0 indicates generally a hot air heating and cirulating assembly incorporating a preferred ernbodiment of the present improved control mechanism.V Heater` I0 includes essentially an inclosing housing II provided with a cold air inlet I2 for the introduction of air from the room or space to be heated, a stove assembly indicated generallyat I3 located within the housing in spaced relation thereto fordefining an air circulating and heating space therebetween and a warm air outlet I4 for removing the hot air to the room or space to be heated.

The stove assembly I3 is preferably in the form of a vertical drum-like section I6 merging with an elongated horizontally 4extending drum-like extension I1 resulting in a generally L shaped stove. Received in vertical drum section I6 is a pot type oil burner I8 the combustion gases from whichvpass up through vertical section I6, horizontal section Il and out through a flue discharge connection I9.

A special arrangement is provided for feeding vfuel oil to pot burner I8 in a mannerwhich effects substantially complete combustion irrespective of the required heighth of fire varying from low fire to high fire or irrespective of transitions from low fire to high re or vice-versa. This arrangement includes an improved construction and relation of structure for directing the air through the heater assembly in a predetermined path and comprises a device forproviding a forced draft at selected intervals. This forced draft is established in response to a demand for increased temperature in the space or room to be'heated 4and the resulting draft .of air forced through the oil to pot burner vI8`.` It will-be'fnotedl that the assembly is made to operate a slow acting heat responsive device to effect a gradual increase in the oil supply to the pot burner following a relatively long time delay of about 4 to 6 minutes from the starting of the forced draft producing device. s ,-7. In the preferredfembodiment illustrated in fiy ure 1 cold air isdrawn in through inlet I2 by means of a blower and forced about the lower` portion of vertical stove section I B in juxtaposi'V10 tion to the pot burner I8 and sent-upwardly out of discharge outlet Il. Vertical partition 2L embraces the horizontal portionof V the ,stoven at a point adjacent to vertical section] separat; j ing the cold air inlet from the warmaroutlet making it necessary for all of the air circulated through the heater to pass through the, blower 20 as indicated by the arrows. For delivering fuel oil to burner pot I8 there is 2;1` providedv athermostatically controlled valveassembly' 'ir`1difca`te`:l `i generally latjj 5 '-comrnun'icat ing 'withtha pot ibur'ne'rj'l 8- through' conduit'v 26. ValveV as'seiriblyid 'includes 'an port g1* and" anoutletportl under the control'bf'afmtgr'st ing v a1l`v e"`2'9jprivdedwith a minimum` flouT "orifl'ce )Schelle t1 o supply a"ininiiriurri-11 amount? o f oil to thebur r 'I8""Whrij the valve' is corn?A pletly`fclose"d maintafin a" *pilo`t 'fiame- Valvev stein an is norm kilyl urged inthe oreridiiectioiif by a cmpressioncoil' spring 1 3 lf. The' exact position of valve 2S i s` fdeterrnined by' a heat responsive device-'indicated generally' are; andprefer-y ablyincluding a tube 33 contaiiiingf'fheat're spprisive liquid suhlas ethyl `alcohol or' itsje'q'uivaient connected 't'lir'oug'hi-conduiti 34 with apres-' rv sure res ponsive member 'indicated at" 35 eifective to urgevalve 29-agairis-t` compression vspring 3l in accordance with the temperature to which tube 3,3, is e'xpo'sed Pressuraf rresponsive member 35 incl`i i'cl efs anadjustable 'assembly '36' varying @the reiaiiiiishiiiiiiid siem 3 `Their11vvfr-21 ,of vali/ c jA ff sfarrai'igedfto besupplied through condui redet'ermineclV headf offfu'elyfoil maintaineddn o'at'control valve housing 4 I.V yThis no at cont olvalve assembly is provided 'with the usual manual control' 42 forv varying theflevel'` oftfuel maintained therein.

` 4It"l has' been" `found f that particularly 'advan` tageo'us results' are obtained where heat responsive vtube 3 3 vis positioned as shown in Figure `1 at' a.l point' Withinj the hilt air SfDiCE:V btwellth'e stovesection I6 4 and Athe surrounding hosingfin opposed`I relation to 'the'4 pot burner and on the opposite "sidefof lstove 'section Gf'frorn' the dis*- cha'rge'foutlet"offblovifer 20j VThis results r'in the very desirableprolo'riged timedelayfbetweenthe starting of theblower land the neessary'fcoolng of the liquidwithin tube 33 for causing the opening of valve' 28 'tojpr'oduce an increased flow'o'f air v from the blower lflrstpa'issesY inheat't'ransmittingrelationship"l with vertical Ys'tovesection I6 before coming incontact with tube 33. In'the more speciflc aspectsl of this invention it willbe notedtliat'the cold air entering'through inlet port I2 rstfreceives' a certain'amount VVof prei heating from horizontal stove section'vIl before passing through-'blower 20 'and aboutvertical section I6 of the stove' and finally in the contact withtube33.y For the purpose lof effectively initiating a transition period 'from low fire v to high flreor the reverse anY adjustable temperature control `thermostat switch is located at'a desired point in the space or room to be heated'and connected 75 in the circuit of the motor 46 which drives blower 20. By having the thermostat 45 effect the closing and opening of the circuit to motor 46 it will now appear that the requisite correlation of oil flow to the burner pot in accordance with .the condition of the ,flamedfor receiving the same will `be effecte'diand there will be a complete combustion of the oil.' In addition to switch45 there is provided a switch 41 responsive to a predetermined temperature for maintaining the blower "circuit openfin.t lie absence of a minimum temi `.perature within the space between vertical section I6 and the housing I I,

(frumi'ng iq Figure 4 there is illustrated sche- 'maticallyjafmodied arrangement incorporating an,alternative' embodiment of the present inven tion. Instead of locating the thermostat l5 in theV space'or-roo'mto be heated there is provided anarrangement of conduits or ducts for de- Y livering hot air from the outlet of the heater toV thel respective zroorns and .additional 4ducts 5I foi-returning the coldair to the heater, the` ther'- mosta'ticlcont'rol devices-'45abelng'placed in the cold vair return ducts i for eilectingustarting and f stopping of the blower motor in accordancawith` the temperature in 'these return ductsn While no arrangement has'been indicated for adjusting the temperature to'whichthe thermostats 45a are'to respond itv willbe i apparent :that a conventional adjustablearrangement maybe provided.

While the' present, inventlonhas been disclosed inconnection with certain :specific embodiments thereof isto be .understood vthat these -are'by wayoifexamplerather than by ,way of limitatio and thatJ the .invention fisy to be defined. by ytheattendanti claims' which' should be given, a scope; asbroad as isconsist'entwiththeprior art.

' We claimrrz, s' ,f -i l: In Iahot` air, heating` yassembly .for heating an inclosed space, including a pot burnerheated stove and assurrounding cabinet,Y definingA an air heating fchamber, therebetween,-means. defining a'cold alrflnlet-.fromfsaid space andal warrrifair,` outlet to'sald spaceymeanslncluding a valve for;y deliveringffueli'oilito said burner; a heat reSDOnf sive device for controllingsaid valve, said device' being/located in the path of airrcirculation at a point subject to. heatradiatlon from said stove` and-anfel'ectricimotor driven airblower for pro ducing'aforced circulation and means for sc. lectivelysy :starting and '-f stopping said blower, whereby the forced.; circulation of air 1 produced by 'said blower upon 1the'same-beingoperated is effective to cool said heat responsive device which 7 iny turn causesithefdelayed.opening of said fuel `heating chamber therebetween, means defining a cold vairinlet from said spaceland a warm air outlet tofsa'id space,l means including a variable flow valve for delivering fuel oil to said burner, a rst heat responsive means' for controlling Vthe degree Aof-Iopeningofsaid-valve, sadirst heat responsive means being located in the path of air circulation at'ra vpoint' subject to heat radiation from saidfstovaan electricfrnotor driven air blower forproducing a forcedl circulatioma .second heatresponsive means for controllini.T said blower operationwsaid secondv heat ,responsive means being located in said inclosed space to be heated, "whereby Vvsaid secondheat responsive means responds to a demandv for heat in said yspace to cause the starting of said blower, the

circulation of air past said rst heat responsive means resulting in a delayed gradual opening ol said fuel valve to build up the burner flame from low re to high re.

3. In a hot air heating assembly for heating an inclosed space, including a pot burner heated stove and a surrounding cabinet dening an air heating chamber therebetween, means deniner a cold air inlet from said space and a warm air outlet to said space, means including a variable ow valve for delivering fuel oil to said burner pot, the combination therewith of means for effecting a transition from low fire to high fire and the reverse with substantially complete combustion, said means comprising a first heat re- .sponsive device for controlling the degree of opening of said valve, said device being located in the path of air circulation at a point also subject to heat radiation from said stove, and an electric motor driven air blower located in said cabinet for producing a forced circulation from said cold air inlet to said warm air outlet, a second heat responsive device for controlling the operation of said blower, said second heat responsive device being located in said inclosed space to be heated, whereby the same responds to a demand for heat to cause the starting of said blower, the resulting circulation of air past said rst heat responsive device effecting a delayed gradual opening of said fuel valve building up the burner flame from low fire to high re.

4. In a hot air heating assembly for heating an inclosed space including a pot burner heated stove and a surrounding cabinet defining an air heating chamber thereabout, said stove being elongated in the horizontal direction and a vertically extending partition dividing said chamber into two vertical compartments intermediate the horizontal extremities of said stove, means defining a cold air inlet from said inclosed space to a rst one of said compartments and means defining a warm air outlet from the other of said compartment to said inclosed space, an electric motor driven air blower for producing a forced circulation from said first compartment to said second compartment, a pot type oil burner in that portion of said stove located in said second compartment, means including an adjustable ow valve for delivering fuel oil to said burner, a rst heat responsive means for controlling the degree of opening of said valve, said rst heat responsive means being located in the path of air circulation through said second compartment at a point between said outlet and said stove also subject to the heat radiation from said stove, a second heat responsive means for controlling operation of said blower, said second heat responsive means being located in Contact with the air from said inclosed space before the temperature of the same is changed by said heating assembly, whereby said second heat responsive means upon a predetermined drop in the temperature thereabout causes the starting of said blower, the resulting circulation of air past said rst heat responsive means cooling the same and causing a gradual delayed opening of said valve to build up said burner ame from low 4re to high re.

MORITZ L. MUELLER. GEORGE R. NEUMANN. 

